“Almost by accident. I notice something. It’s like life, if you’re with someone and they use a certain word or phrase and it keeps recurring. It’s something even they aren’t aware of but you start to notice that. For me it’s like that. I notice something. It’s like a clue, and I start to know the character in a certain way.”

When “Stand Up Guys” opened Friday, it marked the third big-screen turn in four months for Walken, 69, and another to add to his list of 55 films. (His lifetime gross, according to the online industry tracker boxofficemojo.com, is more than $1.6 billion.)

And while you’d be right to consider that a trifecta, you shouldn’t call it a triumverate of the weird. Though the actor with the pregnant pause, the husk of a voice, gets our assumption he’s gonna get odd.

“Early in my career I was in two great movies that came out in the same year, and in both of them I was very disturbed — ‘Annie Hall’ and ‘The Deer Hunter,’“ he said from New York City, where he lives with his wife of four decades, Georgianna Walken, a casting director.

“That was kind of the first impression I made in the movies. And stuff like that can stick. But that’s not something to complain about. It made me a good living and kept me busy for a long time. But it is nice to get away from it once in a while.”

The recent roles have been soulful, beautifully melancholy even.

In “A Late Quartet,” Walken plays Peter, cellist and the father figure in a longstanding string quartet. When he announces that he must retire because he’s been diagnosed with Parkinson’s, his beloved colleagues act out.

Walken re-teamed with playwright-filmmaker Martin McDonagh for fall’s deliriously violent and oddly touching comedy “Seven Psychopaths” (just out on DVD). He’s the mournful Hans, the most gentle of the seven so-called psychopaths.

In “Stand Up Guys,” Walken’s character, Doc, is forced by a mob boss to dispatch friend Val. Al Pacino portrays the gangster, just out of prison after a 28-year bid for not ratting.

There was a time when director Fisher Stevens and the producers were thinking that Walken would play the ex-con and Pacino would portray the sorrowful, burdened friend.

But “It would have been just another Chris Walken strange guy,” says the actor. “I’m glad it worked out the way it did. Al played it way better than I could have and also differently.”

Given how prolific Walken and Pacino are, it’s hard to believe they’ve never appeared onscreen together.

“I’d known Al going back to the Actors Studio when we were kids, “ he says. “It reaffirmed that I knew he was a great actor. To be with him on the set is inspiring. It’s exciting to go to work.”

Walken also had never worked with co-star Alan Arkin, a fact he was happy to remedy.

In ‘Stand Up Guys’ somebody says ‘It’s great to work together.’ And that’s absolutely true.”

About Walken’s kitchen read-throughs. Sometimes, he says, “I cook while I read.” And it’s inviting to imagine the actor, initially schooled in musical theater and known for hoofing in more than a few films (“Deer Hunter,”“Catch Me If You Can”“Hairspray”) sort of dancing, swaying as he reads those scripts.

“The best thing really is to have two scripts at the same time. If I have two scripts they spill over. I’ll find myself doing something in one script that has absolutely nothing to do with that script. It’s from the other script. I think being able to surprise the audience is very important,” says Walken. “You can’t surprise anybody unless you surprise yourself.”